Engine only starts if throttle cable is at a strange angle

[mullan]

I originally posted this under the subject "GS500 engine does not start, ignition cable thingmajig the cause", but I repost this now so it can get the right attention.

For some reason, the bike only starts if either of the throtte cables are pressed against the ignition housing on the right handle bar.  Very hard to explain.  So, if I try to start the bike normally, nothing happens (just a single click sound).  If I grab hold of one of the ignition cables and push it at a certain angle at the point where it inserts into the ignition housing, the bike starts normally.

I opened up the ignition housing to find that the throttle cables have no electricity anywhere near them.  So then I wondered if somehow by moving the throttle cable about I was creating some kind of earth or something?

What can the matter be?

[mullan]

Now even putting the cable at a strange angle isn't helping.  So I am now learning how to push start.  I am short so cannot run sitting on the bike.  I am not confident about jumping on the bike when it is moving either, again being vertically challenged is a problem.  But I saw some guy on youtube push starting in 2nd running beside the bike.  I tried it this morning (with a hot engine, because I did manage to start the bike before I arrived at work.  Thought I'd practice in an empty car park because I just know I need to learn this) and it worked!  There was no locking of the back wheel, like other posts suggest.

I cannot get this obvious-electrical problem repaired until I get 3 more salaries (unless someone tells me what's wrong)   (   

Will doing this push start 2 times a day for 3 months do long-term damage?

(ps, living in Belgium so don't try suggesting hills!)

[mister]

Have you checked the clutch switch?

Michael

[mullan]

Thanks Michael! 

I gave the clutch switch a wiggle before and all seemed connected OK.  However, it's only when manipulating the throttle cable (the one lowest ot the ground) at the point it inserts to the housing of the ingition switch that it can give the chance of an electrical ignition start.  In other words, the opposite side to where the clutch switch is.  The more I read on it, the more it seems like a bad earth/ground somewhere.  I fully tighted the positive and negative connections on the battery, but changed nothing. 

Maybe the throttle cable has a current which I am then putting onto the handlebar which then passes the current into the frame which then passes it back to the negative terminal of the battery?  Sound feasible?  So this suggests a bad earth between the engine and frame, which the throttle cable is "correcting", right?  Where the heck is this bad earth?   

Any ideas?

[the mole]

Push starting will not do any damage, in fact there is no wear on the starter motor so it will last longer!
Your problem is very odd, there is no need for the right switch block to be earthed for it to function correctly.
If you are creating an earth for the motor with the throttle cable, you need to establish a proper earth. Try using a jumper cable from the negative battery terminal to the cylider head or block of the motor. If that works, you have identified the problem.

[mullan]

The Mole: fantastic tip!  Never thought of using jump cables between engine and negative teriminal.  This is one diagnosis idea I have never seen before in all my evening internet searches!  I'll see if I can find a colleague with jump cables and let you know how it goes.

[mullan]

the mole:  nope, didn't work.  It's a real mystery then.....either that, or I need a new part.  However, on the bright side I'm really building muscle on these daily push starts.

The only thing I don't like about the gs500, is there's no kickstart. 

[The Buddha]

I seriously believe your start button metal has wear on it and isn't making contact.
Its a common problem really, I have done a little soldering in there pretty often on the older ones.
Cool.
Buddha.

[mister]

It's either the clutch switch - and maybe the way you sit to start it pushes on a cable there or some shaZam!. Or the starter switch itself even if it Looks good. Cause if it starts (or used to) with that kinda jiggling it must be that, yeah?

Michael

[the mole]

Well, if the jump cable didn't help, you've narrowed down the problem. Its not that you need an earth at the switch block, so that indicates that when you wriggle the throttle cable, its affectingthe starter switch in some way. Maybe the act of wriggling just changes the angle of your thumb on the start button?? I'm trying to work out the ergonomics of what you're doing.....If you are pushing the start button with your right thumb, and holding the clutch in with your left hand (have to hold the clutch for starter to work), then how are you wriggling the throttle cable?

To check if its a bad starter switch as Buddha suggested, you could dismantle the switch and short the contacts together and see if it starts easily.

If not, I still think its worth eliminating the issue of the sidestand and clutch 'safety' switches. To diagnose it, find the sidestand relay under the seat, take off the orange and orange/blue wires and connect them together. This will bypass the relay and therefore the sidestand and clutch switches, see if that makes a difference. You will have to remember to be in neutral when you do this! Also, it will start without you holding the clutch in, so you will have a free hand to wriggle cables/wires.
Good luck!

[mullan]

Hi guys,

Wow, I am overwhelmed by the generousity of people here!  I'm very good and taking things apart and putting them back together, but diagnosis is my weakness.  This really helps.

In fact, it now doesn't even do the trick with the wiggling of throttle cable. Just one click sound.  Something has gradually got worse the last week, so it doesn't work at all now.  Maybe because I had to use the ignition switch a lot more than usual and what little contact there was, is now lost.

In order of what next:  
i) I'll try the ignition switch diagnosis (seems to be the main suspect right now) by bypassing the switch contacts;
ii) then try clutch/side stand things.

QUESTION FOR BUDDHA: If the ignition switch is the issue, you said the switch ".......isn't making contact.......I have done a little soldering in there pretty often on the older ones".  I tried to add a photo of what I am trying to describe, but doesn't seem possible.  So, am I supposed to solder over the worn area at the points of contact?  Kind of replating or filling a cavity, much like dentistry?

Thanks again!
Ian.

[The Buddha]

The start button ... not ignition switch. I almost suspect that is the only one where wear is possible to cause failure.
When they start out life the 2 tiny pin head sized plates are say 1/16 of an inch apart and as you press the start button, they make contact.
As things wear, they start moving further and further apart till they are now 1/8th apart and you can no longer make contact by mashing the start button. Then you wiggle the wires and the part that used to be static AKA, the other part than what is the start button ... that moves and makes contact. Pretty soon that dont happen either.

Upon opening it will be obvious that mashing the start button isn't getting the 2 to touch. You should put solder on both sides and bring them to where they contact and most importantly break contact when you let go.

Of course the tin the solder basically is, wears faster than copper so it will now wear out in less and less time.

Open it up, you cannot miss it, and its never written in any manual. Welcome to motorcycle repair ... not just motorcycle parts replace.

Cool.
Buddha.

[mullan]

Buddha, you are a genius!  I came online to update those who have been so kind to reply.  In fact, all the replies are very helpful and valid, but I think your theory of wear has hit the nail on the head.

I opened up the housing of the ignition button and farted about with it for a bit, trying to find the issue.  A spider made a nest in their and I was thinking there was quite literally a bug in the system.  However, I eventually realised the issue is because the copper and/or plastic components are worn, meaning the distances beetween the 2 tiny pin head sized plates and the copper bridge are too far apart (along the horizontal axis).  Pushing the piece of plastic with the 4 wires soldered to it downards, pushes the 2 tiny pin head sized plates closer to this copper bridge and this always makes the bike start.  No compression with my fingertips = no start.  But, of course, all of this manipulation is impossible with the ignition button housing all put back together.

So, as a temporary fix, I need to get the little copper bridge and the 2 tiny pin head sized plates closer together.  And the only thing I can think of is to add solder to the area to bring the contact close enough.

Although this may not be the usual cause of the trouble I have described - symptons other people have had - I would like to add photos of what I am going to do.  How do I do that?

[mister]

Although this may not be the usual cause of the trouble I have described - symptons other people have had - I would like to add photos of what I am going to do.  How do I do that?

#1: Take photos. maybe resize to 640x480
#2: Upload to Photobucket or Flickr
#3: See above post box and above the smileys are some icons... well, click the icon and it will put an IMG Tag in the post. The URL of the image goes between the tag. Like so {img}http:www.flicker.com/yourimage.jpg{/img} where the {} are actually [] as you'll see when you click the icon
#4: Preview to make sure it works.
#5: Post

Michael

[johnny ro]

dont ignore possibility of using a shim to help close the enlarged gap. I havent looked in it so cant promise but keep it in mind, thinking a cutout piece of plastic bottle gehnid whattever part is moving on you now with the cable.

Solder blobs work too.

Maybe both.

[The Buddha]

Ai ai i i i i i i i i i ... K fine this is capable of stumping any one the first time.

K Its been like 7-8 years since the first time this has hit me.

BTW On my virago recently this hit me in reverse. The enigne stop plates had shorted fried themselves open. Ergo, it was the same in the engine kill or  run position ... yea take that sucker.

Cool.
Buddha.

[The Buddha]

dont ignore possibility of using a shim to help close the enlarged gap. I havent looked in it so cant promise but keep it in mind, thinking a cutout piece of plastic bottle gehnid whattever part is moving on you now with the cable.

Solder blobs work too.

Maybe both.

There is nothign behind to put a platstic bit in ...
You can put a metal plate in front like a shim ... but If it drops in the gap it will bridge the 2 even when the enigne is running ... Can you say instant goats ... yup.

Really a solder spot will build it just enough to get positive contact when mashing the button and disconnect when you let it go
Cool.
Buddha.

[mullan]

Dear all,

And Dear Buddha......who inspired me.  Here is what I did to solve the issue.  The issue was, indeed, wear in the ignition button.  I know you're something of an expert, Buddha, but go gentle with me on the botch job I did.  But it works nonetheless.  Photos can be viewed here http://www.flickr.com/photos/44896353@N02/sets/72157622853207678/show/with/4124044129/
Chose A to E, in that order.

Thanks again!!!!
Ian.